The picture is of a Ginkgo tree in my yard. Every year in late October it changes from green to this lovely shade of yellow. And then, a few weeks later all the leaves fall off- almost overnight. Why do these changes happen? The leaves change color because the chlorophyll in the leaf dies off in preparation for the dormant time of winter. The yellow color was there all along you just couldn’t see it because the green was so dominant. Every fall you’ll see the reds of the maple trees and the browns of many oak trees and a variety of other colors on the trees and eventually on the ground. The change happens as the amount of daylight declines with the approach of winter. Why do trees become dormant in the winter? During the warmer, growing months trees need the food produced by the leaves through photosynthesis. In the winter when there is less daylight and colder days and nights trees and many plants are not growing and so don’t need to produce food through photosynthesis so the leaves drop off the tree for the winter. It also seems to protect the tree from damage. If you’ve ever experienced one of our ice storms that we get in the winter you’ll remember that the evergreen trees, the ones that keep their leaves (maybe you think of them as needles) are often damaged by the accumulation of ice. So trees that loose their leaves in the winter have a better chance of surviving ice and snow. So, enjoy our last few days of a colorful fall. And, maybe you’ll be raking leaves this weekend.
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